Engine condition

[docdoru]

There is a leakage test that shows the Rotax 990 rings and valve seats shape:

0%-15% (excellent)
16%-25% (good)
26%-40% (fair)
41%+ (poor)

 

[Bob Denman]

...And... :dontknow: :bbq::bbq:

 

[daveinva]

There is a leakage test that shows the Rotax 990 rings and valve seats shape:

0%-15% (excellent)
16%-25% (good)
26%-40% (fair)
41%+ (poor)

For those of us who have no idea what you just said, care to share in English please? :joke:

 

[NancysToy]

There is a leakage test that shows the Rotax 990 rings and valve seats shape:

0%-15% (excellent)
16%-25% (good)
26%-40% (fair)
41%+ (poor)

That confirms something I always have suspected. The Rotax 990 & 991 engines are not quite as tight as is generally accepted in the industry. Typically an engine in great condition should generally show only 5 to 10% leakage. An engine that's still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates serious trouble. If these are their numbers, BRP allows more leeway as far as an engine at its best or worst goes. While this would accept 25% leakdown, that would be time for an overhaul in most shops. For race engines we used to like less than 5% for our engines, and would never race one with more than 10% leakdown. 15% would be incredibly loose, IMO, especially in these days of precision machining and very smooth bore cylinders with moly filled rings. Less leakdown = better fuel mileage and more horsepower.

 

[Bootie]

Leakage tests

There is a leakage test that shows the Rotax 990 rings and valve seats shape:

0%-15% (excellent)
16%-25% (good)
26%-40% (fair)
41%+ (poor)

Those look like the figures I use to describe my bladder (urinary) leakage behavior:roflblack:

 

[NancysToy]

Those look like the figures I use to describe my bladder (urinary) leakage behavior:roflblack:

:lecturef_smilie: TMI! :roflblack:

 

[Jeriatric]

3% to 5% - good racing engine
5% to 7% - good street engine
10% - weak
20% - shot

 

[Bob Denman]

Those look like the figures I use to describe my bladder (urinary) leakage behavior:roflblack:

Remind me to NEVER ride behind you on a bumpy road... :yikes: :roflblack:

 

[bzbaeren]

engine stats

I still don't understand what you are trying to tell us, are you saying the engine is weak?:shocked:

 

[Jeriatric]

I still don't understand what you are trying to tell us, are you saying the engine is weak?:shocked:

A leak down test gives feed back on how tightly your valves are seating and how well the piston rings are conforming to the cylinder wall. If the test shows a problem then there are procedures to identify if both or one of the above is causing pressure loss.

On a side note. The looser things are the more oil you'll burn.

 

[docdoru]

On a side note. The looser things are the more oil you'll burn.

:thumbup::doorag:

 

[Chupaca]

when..??

Mostly done when buying a used vehicle. A little more complicated than a compression test. You would usually have it done if you lose power, burn oil or shake rattle and roll... !! :thumbup:

 

[thehawk]

i think this goes a long way to support all the discussion on oil and its consumption. never have had a vehicle i've needed to carry oil for ... but this one. figures like those quoted would have resulted in a teardown on previous stuff i've owned.

as henry gibson would say on laugh-in ... veeeery interesting!! just my .02.

thehawk

 

[Bob Denman]

So is there is a solution available? :dontknow: Hone out the cylinders, better rings with tighter end-gaps, different valve seating configuration??? :shocked:

 

[NancysToy]

So is there is a solution available? :dontknow: Hone out the cylinders, better rings with tighter end-gaps, different valve seating configuration??? :shocked:

Can't hone nicasil cylinders.

 

[Chupaca]

Bore baby bore..!!

awhh :cus: ..!! Bore it out sleeve it stick in some wiseco pistons and rings and git..!! :roflblack:

 

[thehawk]

this kind of discussion might be part of an interesting set of 'talks' (like TicketBait is proposing for SF) to be done by BRP reps at the Owner's Event. some kind of interesting discussion about how much of the nikasil coating 'wears' as the pistons and rings seat and gets down to the hard stuff ... and what affect does that have on the engine components.

for those of us with inquiring minds :roflblack::roflblack::roflblack:

thehawk

 

[Bob Denman]

Can't hone nicasil cylinders.

:shocked: :gaah: I should have checked to see if that's what they had in there before opening my big mouth! pps:

 

[ulflyer]

On a side note. The looser things are the more oil you'll burn.

And we know many (most?) of these motors use a fair amount
of oil between changes. Mine uses about 6-8 oz although I've not kept good record of it. I will from now on as a poor mans monitor of engine condition.

I've always wondered about Rotax since all previous Japanese bikes I've owned used very little, on none, between changes.

 

[Bob Denman]

I wonder if they run them a bit "loose", to help them rev more? :dontknow: